HIV protease is an important chemotherapeutic target for the treatment of AIDS; the most successful treatments developed to date involve combinations of protease inhibitors with nucleoside analogs which inhibit the reverse transcriptase. However, the high mutation rate of the virus makes it possible to select against most of the protease inhibitors which thus far have been developed. Recent work on this project has included several goals: 1. Development of HIV protease mutants with greater stability, particularly to allow NMR studies of the uncomplexed enzyme; 2. Evaluation of a new inhibition strategy based on the use of inhibitors with multiple binding modes; 3. Development of a new NMR approach for inhibitor design. The latter method, called the inter-ligand Overhauser effect, allows the investigation of structural relationships between weakly bound ligands so that they can be combined to yield a single, more potent inhibitor. - HIV protease; proline; NMR; nuclear Overhauser effect; inhibitor binding